1 /* 2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/systemDictionary.hpp" 27 #include "gc_implementation/shared/concurrentGCThread.hpp" 28 #include "oops/instanceRefKlass.hpp" 29 #include "oops/oop.inline.hpp" 30 #include "runtime/init.hpp" 31 #include "runtime/interfaceSupport.hpp" 32 #include "runtime/java.hpp" 33 #include "runtime/javaCalls.hpp" 34 35 // CopyrightVersion 1.2 36 37 int ConcurrentGCThread::_CGC_flag = CGC_nil; 38 39 ConcurrentGCThread::ConcurrentGCThread() : 40 _should_terminate(false), _has_terminated(false) { 41 }; 42 43 void ConcurrentGCThread::create_and_start() { 44 if (os::create_thread(this, os::cgc_thread)) { 45 // XXX: need to set this to low priority 46 // unless "agressive mode" set; priority 47 // should be just less than that of VMThread. 48 os::set_priority(this, NearMaxPriority); 49 if (!_should_terminate && !DisableStartThread) { 50 os::start_thread(this); 51 } 52 } 53 } 54 55 void ConcurrentGCThread::initialize_in_thread() { 56 this->record_stack_base_and_size(); 57 this->initialize_thread_local_storage(); 58 this->set_active_handles(JNIHandleBlock::allocate_block()); 59 // From this time Thread::current() should be working. 60 assert(this == Thread::current(), "just checking"); 61 } 62 63 void ConcurrentGCThread::wait_for_universe_init() { 64 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); 65 while (!is_init_completed() && !_should_terminate) { 66 CGC_lock->wait(Mutex::_no_safepoint_check_flag, 200); 67 } 68 } 69 70 void ConcurrentGCThread::terminate() { 71 // Signal that it is terminated 72 { 73 MutexLockerEx mu(Terminator_lock, 74 Mutex::_no_safepoint_check_flag); 75 _has_terminated = true; 76 Terminator_lock->notify(); 77 } 78 79 // Thread destructor usually does this.. 80 ThreadLocalStorage::set_thread(NULL); 81 } 82 83 static void _sltLoop(JavaThread* thread, TRAPS) { 84 SurrogateLockerThread* slt = (SurrogateLockerThread*)thread; 85 slt->loop(); 86 } 87 88 SurrogateLockerThread::SurrogateLockerThread() : 89 JavaThread(&_sltLoop), 90 _monitor(Mutex::nonleaf, "SLTMonitor"), 91 _buffer(empty) 92 {} 93 94 SurrogateLockerThread* SurrogateLockerThread::make(TRAPS) { 95 Klass* k = 96 SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), 97 true, CHECK_NULL); 98 instanceKlassHandle klass (THREAD, k); 99 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL); 100 101 const char thread_name[] = "Surrogate Locker Thread (Concurrent GC)"; 102 Handle string = java_lang_String::create_from_str(thread_name, CHECK_NULL); 103 104 // Initialize thread_oop to put it into the system threadGroup 105 Handle thread_group (THREAD, Universe::system_thread_group()); 106 JavaValue result(T_VOID); 107 JavaCalls::call_special(&result, thread_oop, 108 klass, 109 vmSymbols::object_initializer_name(), 110 vmSymbols::threadgroup_string_void_signature(), 111 thread_group, 112 string, 113 CHECK_NULL); 114 115 SurrogateLockerThread* res; 116 { 117 MutexLocker mu(Threads_lock); 118 res = new SurrogateLockerThread(); 119 120 // At this point it may be possible that no osthread was created for the 121 // JavaThread due to lack of memory. We would have to throw an exception 122 // in that case. However, since this must work and we do not allow 123 // exceptions anyway, check and abort if this fails. 124 if (res == NULL || res->osthread() == NULL) { 125 vm_exit_during_initialization("java.lang.OutOfMemoryError", 126 "unable to create new native thread"); 127 } 128 java_lang_Thread::set_thread(thread_oop(), res); 129 java_lang_Thread::set_priority(thread_oop(), NearMaxPriority); 130 java_lang_Thread::set_daemon(thread_oop()); 131 132 res->set_threadObj(thread_oop()); 133 Threads::add(res); 134 Thread::start(res); 135 } 136 os::yield(); // This seems to help with initial start-up of SLT 137 return res; 138 } 139 140 void SurrogateLockerThread::manipulatePLL(SLT_msg_type msg) { 141 MutexLockerEx x(&_monitor, Mutex::_no_safepoint_check_flag); 142 assert(_buffer == empty, "Should be empty"); 143 assert(msg != empty, "empty message"); 144 assert(!Heap_lock->owned_by_self(), "Heap_lock owned by requesting thread"); 145 146 _buffer = msg; 147 while (_buffer != empty) { 148 _monitor.notify(); 149 _monitor.wait(Mutex::_no_safepoint_check_flag); 150 } 151 } 152 153 // ======= Surrogate Locker Thread ============= 154 155 void SurrogateLockerThread::loop() { 156 BasicLock pll_basic_lock; 157 SLT_msg_type msg; 158 debug_only(unsigned int owned = 0;) 159 160 while (/* !isTerminated() */ 1) { 161 { 162 MutexLocker x(&_monitor); 163 // Since we are a JavaThread, we can't be here at a safepoint. 164 assert(!SafepointSynchronize::is_at_safepoint(), 165 "SLT is a JavaThread"); 166 // wait for msg buffer to become non-empty 167 while (_buffer == empty) { 168 _monitor.notify(); 169 _monitor.wait(); 170 } 171 msg = _buffer; 172 } 173 switch(msg) { 174 case acquirePLL: { 175 InstanceRefKlass::acquire_pending_list_lock(&pll_basic_lock); 176 debug_only(owned++;) 177 break; 178 } 179 case releaseAndNotifyPLL: { 180 assert(owned > 0, "Don't have PLL"); 181 InstanceRefKlass::release_and_notify_pending_list_lock(&pll_basic_lock); 182 debug_only(owned--;) 183 break; 184 } 185 case empty: 186 default: { 187 guarantee(false,"Unexpected message in _buffer"); 188 break; 189 } 190 } 191 { 192 MutexLocker x(&_monitor); 193 // Since we are a JavaThread, we can't be here at a safepoint. 194 assert(!SafepointSynchronize::is_at_safepoint(), 195 "SLT is a JavaThread"); 196 _buffer = empty; 197 _monitor.notify(); 198 } 199 } 200 assert(!_monitor.owned_by_self(), "Should unlock before exit."); 201 }